The disclosed subject matter relates generally to manufacturing and, more particularly, to using asymmetric templates for forming non-periodic patterns using directed self-assembly materials.
Many technological applications require the ability to pattern precise structures with a periodicity (pitch) below 60 nm. Existing optical lithography is capable of high-throughput processing, but the patterning pitch of a single optical lithography step is limited to about 80 nm. A challenge for lithography is to devise tools, materials, and processes that can reliably, efficiently, and quickly pattern structures with smaller dimensions and reduced pitch.
Directed Self-Assembly (DSA) lithography is a materials-based approach that relies on the phase separation of certain polymeric materials. A basic DSA process consists of coating a polymeric material on a substrate over a previously formed guide structure. The guide pattern is typically formed by an optical lithography process. The polymeric self-assembly material contains two (or more) chemical components that have carefully controlled size. These components can be bonded together into polymer chains known as diblocks, such as A-A-A-A-A-A-A-A-A-A-B-B-B-B-B-B-B-B-B-B. Immediately after coating, the A and B components are relatively disordered, however, these components (A, B) can be induced to separate into distinct phases and thereby form features with a characteristic pitch that is defined by the chemical composition. By coating this polymer on a substrate with a pre-formed guide pattern, it is possible to “interpolate” the features between the elements of the guide pattern and reduce the pitch by a factor of 2-40 relative to the guide pattern.
While DSA has shown promise in creating large areas of straight line/space patterns with constant pitch, it is difficult to pattern lines of varying pitch and/or dimensions. Such structures are useful for semiconductor device applications.
This section of this document is intended to introduce various aspects of art that may be related to various aspects of the disclosed subject matter described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the disclosed subject matter. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art. The disclosed subject matter is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.